The present invention relates to an eyeglass lens processing apparatus for processing a peripheral edge of an eyeglass lens.
As a method of forming a bevel used to support an eyeglass lens using a groove of a rim of an eyeglass frame, there are known a method based on a lens front surface curve (front curve based), a method based on a lens rear surface curve (rear curve based), and a method of dividing an edge thickness by a predetermined ratio. Generally, the method corresponding to a lens shape is used. When a frame curve is largely different from the bevel curve set by means of those methods, the lens having the bevel formed thereon cannot be inserted into the rim in some cases. As a method of coping with this problem, there are proposed various methods of tilting the bevel curve in accordance with the frame curve (Japanese Patent Application Laid-Open No. H11-70451 (U.S. Pat. No. 6,095,896) and Japanese Patent Application Laid open No. 2006-142473).
However, in the known method of tilting the bevel curve, it is necessary for an operator to consider a tilt amount and a tilt direction of the bevel curve in order to dispose the bevel having a good appearance, and it is difficult for an operator who is not accustomed to a processing operation to set the appropriate bevel. Additionally, in the method of determining the bevel curve in accordance with the frame curve at the first time and tilting the bevel curve, the bevel curve cannot be disposed within the edge thickness of the lens in some cases. In this case, the operator needs to check the bevel curve value again whenever the tilt amount and the tilt direction of the bevel curve are changed. As a result, it takes trouble to form the bevel having a good appearance.